Hearing loss affects over 31 million people in the United States. As a chronic condition, the incidence of hearing impairment rivals that of heart disease and, like heart disease, the incidence of hearing impairment increases sharply with age.
Hearing loss can also be classified in terms of being conductive, sensorineural, or a combination of both. Conductive hearing impairment typically results from diseases or disorders that limit the transmission of sound through the middle ear. Most conductive impairments can be treated medically or surgically. Purely conductive hearing loss represents a relatively small portion of the total hearing impaired population.
Sensorineural hearing losses occur mostly in the inner ear and account for the vast majority of hearing impairment (estimated at 90-95% of the total hearing impaired population). Sensorineural hearing impairment (sometimes called “nerve loss”) is largely caused by damage to the sensory hair cells inside the cochlea. Sensorineural hearing impairment occurs naturally as a result of aging or prolonged exposure to loud music and noise. This type of hearing loss cannot be reversed nor can it be medically or surgically treated; however, the use of properly fitted hearing devices can improve the individual's quality of life.
Conventional hearing devices are the most common devices used to treat mild to severe sensorineural hearing impairment. These are acoustic devices that amplify sound to the tympanic membrane. These devices are individually customizable to the patient's physical and acoustical characteristics over four to six separate visits to an audiologist or hearing instrument specialist. Such devices generally comprise a microphone, amplifier, battery, and speaker. Recently, hearing device manufacturers have increased the sophistication of sound processing, often using digital technology, to provide features such as programmability and multi-band compression. Although these devices have been miniaturized and are less obtrusive, they are still visible and have major acoustic limitation.
In a parallel trend, the advent of music players and cell phones has driven the demand for small and portable headphones that can reproduce sound with high fidelity so that the user can listen to the sound without disturbing people who are nearby. These headphones typically use small speakers that can render the sound. With cell phones, there is a need to capture the user's voice with a microphone and relay the voice over the cellular network so that the parties can engage in a conversation even though they are separated by great distances. Microphones are transducers just like speakers. They change sound waves into electrical signals, while speakers change electrical signals into sound waves. When a headphone is equipped with a small microphone, it is called a headset.
A headset may be used in conjunction with a telephone device for several reasons. With a headset, the user is relived of the need to hold the phone and thus retains his or her hands free to perform other functions. Headsets also function to position the earphone and microphone portions of a telephone close to the user's head to provide for clearer reception and transmission of audio signals with less interference from background noise. Headsets may be used with telephones, computers, cellular telephones, and other devices.
The wireless industry has launched several after-market products to free the user from holding the phone while making phone calls. For example, various headsets are manufactured with an earpiece connected to a microphone and most of these headsets or hands-free kits are compatible with any phone brand or model. A possible headset can be plugged-in to the phone and comprise a microphone connected via wires to the headset so that the microphone, when in position, can appropriately capture the voice of the user. Other headsets are built in with a Bluetooth chip, or other wireless means, so that the voice conversation can be wirelessly diverted from the phone to the earpiece of the headset. The Bluetooth radio chip acts as a connector between the headset and a Bluetooth chip of the cell-phone.
The ability to correctly identify voiced and unvoiced speech is critical to many speech applications including speech recognition, speaker verification, noise suppression, and many others. In a typical acoustic application, speech from a human speaker is captured and transmitted to a receiver in a different location. In the speaker's environment there may exist one or more noise sources that pollute the speech signal, or the signal of interest, with unwanted acoustic noise. This makes it difficult or impossible for the receiver, whether human or machine, to understand the user's speech.
United States Patent 20080019557 describes a headset which includes a metal or metallic housing to which various accessory components can be attached. These components can include an ear loop, a necklace for the holding of the headset while not being worn on the ear, an external mount, and other components. The components include a magnet which facilitates mounting to the headset. The components are not restricted to a particular attachment point, which enhances the ability of the user to adjust the geometry for better fit.
With conventional headsets, people nearby can notice when the user is wearing the headset. U.S. Pat. No. 7,076,077 discloses a bone conduction headset which is inconspicuous in appearance during wearing. The bone conduction headset includes a band running around a back part of the user's head; a fastening portion formed in each of opposite end portions of the band; a bone conduction speaker provided with a knob which is engaged with the fastening portion; and, an ear engagement portion, which runs over the bone conduction speaker during wearing of the headset to reach and engage with the user's ear. An extension of either the fastening portion in the band or a casing of the bone conduction speaker may be formed into the ear engagement portion.
U.S. Pat. No. 7,246,058 discloses a system for detecting voiced and unvoiced speech in acoustic signals having varying levels of background noise. The systems receive acoustic signals at two microphones, and generate difference parameters between the acoustic signals received at each of the two microphones. The difference parameters are representative of the relative difference in signal gain between portions of the received acoustic signals. The systems identify information of the acoustic signals as unvoiced speech when the difference parameters exceed a first threshold, and identify information of the acoustic signals as voiced speech when the difference parameters exceed a second threshold. Further, embodiments of the systems include non-acoustic sensors that receive physiological information to aid in identifying voiced speech.